blueberry train wreck. >> how much pot do you have to smoke before you have trouble driving? >> i feel normal. >> our cbs station in seattle conducted a test where three drivers got high and drove on a controlled track. turns out, all of them slow down significantly. when this driver measured seven times washington state's legal limit for marijuana -- >> i hit a cone. i see it. >> she hit a cone. the instructor said she is still okay. >> not yet. >> well, you do drive slower. >> these teenagers had mixed feelings about the subject, but they do believe alcohol is way more dangerous. >> it says, stoned driver will stop at a stop sign and wait until it turns green and a drunk driver will run that stop sign and it doesn't turn green. so, safe drivers. they are safe. >> it has very little effect on the cause of accidents. >> clint is the author of marijuana, gateway to hell. >> if people compensate and more thoughtful when they're driving while they're high, then they're driving better. >> one time in your life, you get to do this, you should do it. >> yeah. >> by the end of the t